The present invention relates to a method of forming compound lenses, particularly triplet lenses, in which multiple lens elements are integrally molded.
Compound lenses include multiple lenses arranged to provide a desired optical feature. Compound lenses are often used in imaging, for example with cameras or telescopes, to correct for optical aberrations. A triplet lens is a compound lens that includes three individual lenses arranged to correct for chromatic and spherical aberrations. The individual lenses can be spaced apart, such as in a Cooke triplet, or bonded together. Two common types of bonded triplets are the Steinheil triplet and the Hastings triplet. The Steinheil triplet includes a low refractive index center lens bonded with identical high refractive index outer lenses. The Hastings triplet includes a high refractive index center lens bonded with identical low refractive index outer lenses. A Hastings triplet is commonly used for making magnifying devices, such as a jeweler's loupe.
The individual lenses in a Steinheil or Hastings triplet are bonded together using an adhesive, such as a transparent optical bonding cement. Bonding the individual lenses together can be time consuming and if not done correctly, can negatively affect the optical properties of triplet. For example, if a crown lens is not centered on the flint, the light transmitted through the triplet may not be focused. In addition, the adhesive used in bonding the lenses can degrade over time or when exposed to a suitable solvent, which may cause the lenses to shift or separate from one another.
It would therefore be beneficial to provide a process for forming a triplet lens without the use of an adhesive to bond the individual lenses together. It would also be beneficial to provide a lens that exhibits optical features similar to a compound lens without the use of multiple individual lenses.